textproduct: Quad Cities

KEY MESSAGES

- An active weather pattern continues through the weekend with rounds of rain, heavy at times. There will be brief dry periods between each round.

- Additional rainfall of 2-3 inches through Monday is becoming likely (50-80%) across eastern Iowa and northwest Illinois, keeping a risk of flash flooding around. Localized areas of 5+ inches remain possible (5-15%) which could lead to sharp rises in small streams and creeks.

SHORT TERM /THROUGH THURSDAY NIGHT/

Issued at 159 AM CDT Wed Sep 16 2026

A stationary front across northern Missouri and central Illinois will keep scattered showers (50-70% coverage) along and south of I-80, supported by an area of shear vorticity left behind from Tuesday's trough passage. While the severe threat is very low (less than 5%), heavy rainfall remains the primary hazard, especially south of Highway 34 where some locations already received over 3 inches of rain already. There should a break this afternoon/evening before a second weak shortwave invigorates more showers and storms (50-80% coverage) along and north of I-80 that will last into Thursday morning. Latest CAM guidance is hinting towards a narrow band of 1-3 inches near the I-80 corridor, but this is prone to shift with future model runs. While portions of our western counties along and south of I-80 is now primed for flash flooding, opted not to issue a Flood Watch at this time given the uncertainty in the heavy rain axis tonight. The WPC has a Slight (level 2 of 4) risk for excessive rainfall for areas along and south of Hwy 20.

Another notable feature is a lobe of mid-level vorticity being pulled northward from the subtropical Pacific by a shortwave trough over the western CONUS. Surface cyclogenesis is expected along the leeward side of the Rockies in Colorado tonight into Thursday in response to the new forcing, and this new low will play a key role in the generation of more storms heading into the weekend.

Outside of Thursday morning though, mostly dry conditions are in the cards for Thursday afternoon and night as there is little support aloft for showers. Northeasterly flow and cloud cover should keep highs seasonable in the mid-70s to low 80s and lows in the 60s areawide.

LONG TERM /FRIDAY THROUGH TUESDAY/

Issued at 159 AM CDT Wed Sep 16 2026

Friday-Saturday...The low pressure over Colorado will move northward into the Dakotas and Minnesota and produce a WAA wing across eastern Iowa in association with a warm front. Scattered showers and storms (40-80% coverage) are likely to form along this boundary and move northeastward into Wisconsin. Overnight Friday, the mid-level trough finally reaches the northern edge of the ridge over the south-central CONUS and is ejected eastward, pulling the low pressure into northern Iowa. With the enhanced surface convergence and a sufficiently moist air mass (PWATs near 2 inches), widespread storms (60-80% coverage) are expected across the region through Saturday afternoon. Muggy conditions are favored to return with dew points in the upper 60s to low 70s (60-90% chance).

Sunday-Tuesday...A surface pressure over Ontario pushes the low pressure over Iowa southward into Missouri as the shortwave over the western CONUS finally propagates eastward. Mid-level CVA from the trough should support storm development north of the low pressure Sunday into Monday before the system moves into Illinois and Indiana. CAA to kick in as the trough swings through the area, leading to a decrease in PoPs Tuesday and allowing cooler, drier air to move in.

With nearly daily PoPS through Monday and unseasonably high PWATs, additional rainfall of 2-3 inches is likely (50-80%) across portions of eastern Iowa and northwest Illinois with localized areas of 5+ inches possible (5-15%). With most of the CWA already receiving 1-3+ inches over the last 48 hours, the flash flooding threat will become more elevated after each round of heavy rain, and small creeks and tributaries could see sharp rises in short periods of time.

AVIATION /06Z TAFS THROUGH 06Z THURSDAY/

Issued at 1243 AM CDT Wed Sep 16 2026

Widespread showers with isolated embedded thunderstorms are moving across our southeastern CWA and will impact BRL and MLI over the next few hours. Brief periods of MVFR visibilities are possible in heavier showers. After sunrise, another round of showers could impact BRL and MLI as an MVFR cloud deck moves in from the south, eventually reaching CID and DBQ in the afternoon. Ceilings will generally stay between 1500 and 2500 feet with occasional reductions to IFR conditions (30-40% chance) near BRL and MLI. Towards the end of the TAF period, there is a small chance (10-20%) that an isolated thunderstorm develops near CID, but a PROB30 was not included with this issuance.

DVN WATCHES/WARNINGS/ADVISORIES

IA...None. IL...None. MO...None.